Shock and/or vibration sensors have been mounted on disk drive printed circuit boards (PCBs), and have been used to help prevent mechanical disturbances from causing a write in progress to stray excessively off track and destroy previously written data on adjacent tracks. The vibration and shock sensors have been mounted on the PCBs because of a substantial advantage in ease of assembly.
Piezo electric transducers that are used as shock or vibration sensors have been mounted on the disk drive PCB at an angle, so as to have some sensitivity to shock and/or vibration x, y, and z components. In theory the shock sensor is blind (i.e. zero sensitivity) in one axis, but because practical shocks cause multiple modes of vibration response, the sensitivity is practically never zero.
However, as track density increases (i.e. the spacing between concentric data tracks written on the disk decreases), the requirements for sensor speed (quicker response) and sensitivity increase.
Disk drive PCBs typically include capacitors, and ceramic capacitor technology has compressed capacitance into thinner smaller packages. However, the ceramic capacitors induce more vibration on the PCB. Vibration reduced ceramic capacitors are being offered but are undesirably larger for the same capacitance.
Hence, there is a need in the art for more sensitive and quicker responding shock and vibration sensing in disk drive applications.